Project description:RPS3, a universal core component of the 40S ribosomal subunit, interacts with mRNA at the entry channel. Whether RPS3 mRNA-binding contributes to specific mRNA translation and ribosome specialization in mammalian cells is unknown. Here we mutated RPS3 mRNA-contacting residues R116, R146 and K148 and report their impact on cellular and viral translation. R116D weakened cap-proximal initiation and promoted leaky scanning, while R146D had the opposite effect. Additionally, R146D and K148D displayed contrasting effects on start-codon fidelity. Translatome analysis uncovered common differentially translated genes of which the downregulated set bears long 5’UTR and weak AUG context, suggesting a stabilizing role during scanning and AUG selection. We identified an RPS3-dependent regulatory sequence (RPS3RS) in the sub-genomic 5’UTR of SARS-CoV-2 consisting of a CUG initiation codon and a downstream element that is also the viral transcription regulatory sequence (TRS). Furthermore, RPS3 mRNA-binding residues were essential for SARS-CoV-2 NSP1-mediated inhibition of host translation and for its ribosomal binding. Intriguingly, NSP1-induced mRNA degradation was also reduced in R116D cells, indicating that mRNA decay occurs in the ribosome context. Thus, RPS3 mRNA-binding residues have multiple translation regulatory functions and are exploited by SARS-CoV-2 in various ways to influence host and viral mRNA translation and stability.
Project description:The human ribosomal protein S3 (RPS3), a component of the small 40S ribosomal subunit, is mainly involved in ribosomal maturation and initiation of translation through association with initiation factors. In this study, we firstly identified that RPS3 played an important role in HCC progression. We performed RNA sequencing to profile gene expression patterns before and after RPS3 knockdown.
Project description:Angiotensin II (Ang II) treatment contributes to hypertrophic growth and mitochondrial dysfunction in hiPSC-derived cardiomyocytes. Here, we report enhanced RPS3 phosphorylation at serine 149 in nuclear compartment and abnormal mitochondrial biogenesis during Ang II incubation. Furthermore, RPS3 S149 mutation attenuated Ang II induced cardiomyocyte hypertrophy and improved mitochondrial biogenesis and dysfunction. Mechanistically, RPS3 Ser149 mutation promoted mitochondrial RNA stabilization and blunt Ang II induced mitochodnrial RNA alternative splicing for degradation, by which RPS3 dephosphorylation restored mitochondrial complex assembly in cardiomyocytes.
Project description:Control of mRNA poly(A) tail has central role to regulate mRNA metabolism: translation efficiency and mRNA stability. Gene expression in maturing oocytes largely relies on the regulation of mRNA metabolism as they are transcriptionally silent. The CCR4-NOT complex is a major deadenylase for mammals and regulates poly(A) tails of maternal mRNAs, however their function to translational regulation was not well understood. Here we show that CCR4-NOT suppresses translational activity of maternal mRNAs during oocyte maturation. Oocytes which lack entire deadenylase activity of CCR4-NOT by genetic deletion of its catalytic subunits: CNOT7 and CNOT8 showed increase of both expression of maternal mRNAs and translational activity of them during oocyte maturation.
Project description:Piwi-interacting small RNAs (piRNAs) of fetal prospermatogonia of mice have been strongly implicated in transposon control. In contrast, little is known about biogenesis and function of abundant piRNAs from adult testes expressed in late spermatocytes and round spermatids. These so-called "pachytene" piRNAs are processed from long non-coding piRNA precursors and have no defined RNA targets in the transcriptome even though their binding partner Piwi, MIWI, is essential for spermiogenesis and fertility. Here we report that 129SvJae mice lacking Maelstrom (MAEL), a conserved piRNA pathway protein, exhibit spermiogenic arrest with defects in acrosome and flagellum formation. Further analysis revealed MAEL association with RNPs containing MIWI, TDRD6, and processed intermediates of pachytene piRNA precursors of various length. Loss of MAEL causes a 10-fold drop in pachytene piRNA levels but an increase in piRNAs from abundantly expressed mRNAs. These results suggest a MAEL-dependent mechanism for the selective processing of pachytene piRNA precursor into piRNAs. Strikingly, ribosome profiling of Mael-null testes revealed that reduced piRNA production is accompanied by reduced translation of over 800 spermiogenic mRNAs including those encoding acrosome and flagellum proteins. In light of recent reports of piRNA-independent protection of translationally repressed mRNPs by MIWI and piRNA-dependent turnover of MIWI, we propose that pachytene piRNAs function by controlling the availably of MIWI for the translational repression of spermiogenic mRNAs. piRNA sequencing, RNA immunoprecipitation, and expression measurements (RNA-Seq and ribosome profiling) in wild-type and Mael -/- testes
Project description:Genome-wide profiling establishes that human cytomegalovirus (HCMV) exerts an extensive, unforeseen level of specific control over which cellular mRNAs are recruited to or excluded from polyribosomes. The landscape of translationally-regulated host mRNAs regulates HCMV replication. The HCMV imposed translational signature shares similarities with cancer cells Two biological replicate experiments were performed profiling total and polysomal mRNAs from i) HCMV-infected vs mock-infected cells and ii) uninfected cells transduced with a lentivirus expressing doxycyclin (dox)-inducible HCMV UL38 +/- dox. Analysis of translationally-controlled host genes in HCMV-infected cell and cells expressing the HCMV UL38 gene product
Project description:Changes in translational efficiency of mRNAs consequent on alteration of HIF and/or mTOR pathway activity in VHL-defective kidney cancer cell were analysed. High-resolution polysome profiling followed by sequencing of the 5′ ends of mRNAs (HP5) was used to measure translational efficiency of mRNAs resolved by their transcription start sites. HP5 was applied to VHL-defective kidney cancer cell lines with or without VHL reintroduction and/or mTOR inhibition with Torin 1 treatment. In addition, the contribution of HIF2A/EIF4E2 pathway was assessed using 786-O cells in which EIF4E2 was inactivated.